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AD9361 DC offset calibration

Question asked by jfp on Mar 29, 2016
Latest reply on Apr 7, 2016 by jfp

Hi,

 

We are working with FMCOMMS3 board. We are trying to transmit a test signal (white noise filtered) from the Tx1 antenna to the Rx1 antenna. We set maximun attenuation at the Tx1 (70000 mdB) and maximun gain at the Rx1 (70dB). We gradually reduce the attenuation level (making sure that the receiver is not saturated). The thing is when we reach an attenuation level of 20000 mdB the received signal presents the strange behaviour (in time domain) showed in the figure.

 

DC.png

 

Disabling the BB DC tracking (ad9361_set_rx_bbdc_track_en_dis) this strange behaviour disappear but the DC level is huge.

 

Is the DC compensation algorithm the reason of this strange behaviour? How could we avoid this?

 

Thanks in advance,

 

Juan.

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